feat: avoid scanner during build and only optimize CJS in SSR

[patak-dev]

Description

Follow up to:

• feat: improved cold start using deps scanner #8869

That enabled back the scanner also during build to fix:

• optimizeDeps does not process aliased imports #8867

This PR avoids the scanner by refactoring preAlias to register the aliased dependency when needed.

With this, we also now support aliased optimized deps when added in an import by a plugin. This was failing before because they were invisible to the scanner

The PR now also implements the change in heuristics to what needs to be optimized during SSR. Only no-external CJS deps will be optimized during SSR, the user can opt-in using ssr.optimizeDeps.include

Some details:

• If a dependency is aliased, it isn't optimized by default even if the replacement is CJS. Users can include it to be optimized. We could support this by loading the entry and using mlly, or by recursively finding the package.json to see if the replacement is in a commonjs or module context. I don't know if the complexity is worth it.
• Added 'vitepress' to optimizeDeps.exclude since it is aliased with replacement join(DIST_CLIENT_PATH, '/index'), and in it a virtual module is used. This was not a problem with commonjs during build, but now dependencies need to be excluded if they are using Vite features.

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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